document.write( "Question 1156986: 4 couples (8 people) are getting on a double-decker bus that has 4 seats on each floor. How many different ways can they sit on the bus so that each person's partner is on the opposite floor?\r
\n" ); document.write( "\n" ); document.write( "My try was 2 ways to select the floor.
\n" ); document.write( "2 ways to select a person from each couple. So 2^4 = 16 ways to select a person from all the 4 couples.
\n" ); document.write( "Also to arrange 4 persons on the top floor 4! and to arrange 4 persons on the bottom floor 4!.
\n" ); document.write( "So 2 * 2^4 * 4! * 4! = 18432 ways. \n" ); document.write( "

Algebra.Com's Answer #779983 by ikleyn(52781) $\"\"$ $\"About$

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document.write( " = 16 ways to select a person from each and all the 4 couples,\r\n" );
document.write( "                    to send him (or her) to the upper deck.\r\n" );
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document.write( "4! = 24 ways to order people on the bottom floor.\r\n" );
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document.write( "4! = 24 ways to order people on the upper floor.\r\n" );
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document.write( "In all,  16 * 24 * 24 = 9216 ways.    ANSWER\r\n" );
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